Acne is a disorder resulting from the actions of hormones on the sebaceous glands, which leads to plugged pores and outbreaks of lesions, commonly called pimples. Nearly 17 million people in the United States have acne, making it the most common skin disease. Severe acne can lead to disfiguring, permanent scarring.
Acne is described as a disorder of the pilosebaceous units (PSUs). Found over most of the body, PSUs consist of a sebaceous gland connected to a canal, called a follicle that contains a fine hair. These units are most numerous on the face, upper back and chest. The sebaceous glands make an oily substance called sebum that normally empties onto the skin surface through the opening of the follicle, also called a pore. Cells called keratinocytes line the follicle.
The hair, sebum and keratinocytes that fill the narrow follicle may produce a plug, which is an early sign of acne. The plug prevents sebum from reaching the surface of the skin through a pore. The mixture of oil and cells allows bacteria Propionibacterium acnes (P. acnes) that normally live on the skin to grow in the plugged follicles. The bacteria produce chemicals and enzymes and attract white blood cells that cause inflammation. Then the wall of the plugged follicle breaks down, the sebum, shed skin cells and bacteria disseminate into the nearby tissues, leading to lesions or pimples.
For patients with moderate to severe acne, the doctor often prescribes oral antibiotics. Oral antibiotics are thought to help control acne by curbing the growth of bacteria and reducing inflammation. Tetracyclines have been used because of their anti-bacterial and anti-inflammatory properties.